Not Applicable.
The present invention relates to medical devices, and particularly to prosthetic implant components, and more particularly to an implantable artificial spinal disc.
Advancing age, as well as injuries, can lead to changes in the various bones, discs, joints, and ligaments of the body. Such changes and injuries often manifest themselves in the form of damage or degeneration of a spinal disc, the result of which is mild to severe chronic back pain. Under certain circumstances, this pain can be lessened or completely alleviated by removal of the damaged or degenerated spinal disc, followed by the implantation of an artificial intervertebral disc.
Many artificial intervertebral discs are known, such as those disclosed in U.S. Pat. Nos. 5,893,889 to Harrington, U.S. Pat. No. 5,683,465 to Shinn et al.5,674,294 to Bainville et al., U.S. Pat. No. 5,458,643 to Oka et al., U.S. Pat. No. 5,306,309 to Wagner et al., U.S. Pat. No. 5,246,458 to Graham, and U.S. Pat. No. 4,759,769 to Hedman. There remains a need, however, to substantially simulate a healthy spinal disc, while still allowing for ease of insertion and/or removal of the prosthetic device, and while providing adequate protection against expulsion of the implanted prosthetic disc. Thus, it remains a goal in the art to produce a prosthetic device, such as an artificial intervertebral disc, that possesses these properties.
The present invention provides an implantable prosthetic element. Although the invention is primarily shown and described as an artificial disc prosthesis, it is understood that the invention has other applications as well, such as for use as an ankle or heel prosthesis.
The implantable prosthetic element has a first end plate and a second end plate, each of which has a bone-facing surface and an opposed mating surface. The bone-facing surfaces of the first end plate and the second end plate each have a plurality of lobes protruding therefrom. An elastomeric core is interposed between and attached to the mating surfaces of the first end plate and the second end plate. The prosthetic element is constructed such that the thickness is greater at the anterior side than at the posterior side. As a result, the lobe surface is generally oriented at an angle, sloping from the anterior to the posterior side.
Some or all of the plurality of lobes include one or more wedge-like fins which protrude therefrom. The lobes may also include a plurality of surface features that promote osteo-integration.
In one embodiment of the present invention, the first end plate and the second end plate each contain two lobes, with a slot separating the two lobes of each end plate. Each slot may optionally include one or more recesses to facilitate insertion and/or extraction of the element from its implantation site.